This invention relates to a process for the preparation of optically active 6-hydroxymethyl-4-(tert-butyldimethylsilyloxy)-(4S,6R)-tetrahydro-2H-2-pyranone (xcex2 Hydroxy-xcex4-Lactone) having formula 1. 
More particularly it relates to a process for the preparation of the said compound using compound having formula 5, which was obtained from Cis, cis-3,5-di(methylcarbo 
nyloxy)cyclohexylacetate having formula 2 by following the earlier patent procedure. 
Hitherto known processes for the synthesis of xcex2-hydroxy-xcex4-lactone (1) involves
a) Enzymatic kinetic resolution of racemic xcex2-hydroxy-xcex4-lactone by transesterification with vinyl acetate in THF using Chromobacteriun viscosum lipase as catalyst at 40xc2x0 C. [Crosby, J. B.; Andrew, J. H.; John, A. L. WO 9306235 A1 CA 119:936292 (1993)]
b) Chemoenzymatic route involving kinetic resolution through lactone formation in ether catalyzed by PPL [Bonini, C.; Pucci, P.; Viggiani, L. J. Org. Chem. 1991, 56,4050]
c) Chemoenzymatic route involving enzymatic desymmetrization of intermediate diacetate, followed by chemical conversions. [Bonni, C.; Racioppi, R.; Righi, G.; Viggiani, L. J. Org. Chem. 1991, 58, 802]
The prior art processes have following drawbacks:
1. The processes use chemicals such as butyl lithium, lithium aluminum hydride, methoxydiethylborane that are costly and difficult to handle and therefore make the process difficult.
2. All known process are however involves large number of synthetic steps resulting in low over all yields.
The main object of the present invention is to provide a new process for the preparation of xcex2-hydroxy-xcex4-lactone (1), which obviates the drawbacks of the prior art processes and use cheaper and easily accessible chemicals.
Another object of the present invention is to provide (i) selective Baeyer-Villiger rearrangement of 3-hydroxy-5-t-butyldimethylsilyloxy-1-cyclohexanone (7) with chemical reagent or Baeyer Villiger oxidase and (ii) enantioselective hydrolysis of cis-3-(methylcarbonyloxy)-5-(tert-butyldimethylsilyloxy)cyclohexylacetate with enzyme. (iii) mild enzymatic hydrolysis of 3-oxo-5-(tert.butyldimethylsilyloxy)-(1S, 5S)-cyclohexylacetate (6) wherein xcex2-elimination is suppressed and optical purity is enhanced through kinetic resolution.
Accordingly the present invention provides a process for the preparation of 6-Hydroxy methyle-4-(tert-butyl dimethylsilyloxy)-(4R, 6S)-tetra hydro 2H-2-pyranone of formula 1 using novel intermediates which comprises
a) reacting 3-hydroxy-5-(tert.butyldimethylsilyloxy)-(1S,3R,5R)-cyclohexylacetate having formula 5 in an organic solvent preferably chloroalkanes with chlorochromate of tertiary amines at temperature ranging from 10 to 30xc2x0 C., quenching the reaction by adding of diethyl ether, filtering the mixture through ceilite and washing with brine, removing the solvent by evaporation, followed by fast column filtration to obtain 3-oxo-5-(tert.butyldimethylsilyloxy)-(1S, 5S)-cyclohexylacetate having formula 6, 
b) hydrolysing 3-oxo-5-(tert.butyldimethylsilyloxy)-(1S, 5S)-cyclohexylacetate having formula 6 with lipase enzyme in a buffer having pH range of 5 to 7, at a temperature ranging from 25 to 30xc2x0 C. for a period ranging between 24 to 48 hr, extracting the mixture with an organic solvent, removing the solvent by evaporation and on column chromatography to obtain 3-hydroxy-5-(tert-butyldimethyl silyloxy)-(3R,5S)-cyclohexan-1-one having formula 7, 
c) reacting 3-hydroxy-5-(tert-butyldimethyl silyloxy)-(3R,5S)-cyclohexan-1-one having formula 7 with m-chloroperbezoic acid at room temperature for the period ranging from 16-24 hours, extracting with organic layer, washing with sodium metabisulphite, brine, drying and on evaporation to obtain 6-hydroxymethyl-4-(tert-butyldimethylsilyloxy)-(4S,6R)-tetrahydro-2H-2-pyranone having formula 1,
In another embodiments of the present invention the organic solvent used in steps a-c for the extraction of the product is selected from the group consisting of ethyl acetate, chloroform and dichloromethane.
In another embodiments of the present invention the buffer used in steps b for the reaction is selected from phosphate buffer and citrate buffer.
In another embodiments of the present invention the lipase used in steps b for the reaction is selected from the group consisting of pig procain lipase (PPL), pig liver esterase (PLE) and chicken liver acetone powder (CLAP).
In yet another embodiment of the present invention the enzymatic hydrolysis used in step b is mild and suppresses B-elimination along with enhancement in optical purity.
In yet another embodiment the oxidising agent used is selected from the group consistting of chloroperbenzoic acid, hydrogen peroxide and per acetic acid.
In yet another embodiment the present invention provides a compound 3-oxo-5 (tert.butyldimethylsilyloxy-(1S,5S)-cyclohexylacetate having formula 6 
In yet another embodiment the present invention provides a compound 3-hydroxy-5-(tert-butyldimethyl silyloxy)-(3R,5S)-cyclohexane-1-one having formula 7 
The process of the present invention is described herein below with references to the following examples, which are illustrative only and should not be construed to limit the scope of the present invention in any manner.
The novel components having formulae 3 to 5 have been claimed in our co-pending application No. 09/783,749.